1. Field of the Invention
The invention relates to a device for distributing flowing media over a flow cross section and, in particular, to a device comprising a distributor plate which extends over the flow cross section and has a multiplicity of openings, and a cover plate having passages and arranged so as to determine the free passage cross section of all openings of the distributor plate.
2. Description of the Prior Art
Devices of the above type are required, for example, in installations for chemical processes, where in a chamber filled with packing, the packing is to be brought into contact with a gaseous or liquid medium as uniformly as possible. They are also used when aerating liquids with gases where it is necessary to introduce the gas into the chamber filled with liquid with a distribution as uniform as possible. Finally, such devices also find use in applications in which a cylindrical chamber filled with a catalyst is to be supplied from a narrower supply pipe of gaseous reactants, in such a manner that the reactants are distributed over the entire chamber cross section as uniformly as posssible, so that the catalyst is loaded as uniformly as possible.
According to the investigation by Hagen and Poiseuille, there is, in media flowing pipes, usually a core flow with increased flow rate in the center of the pipe, but a decelerated flow with low flow rate at the walls of the pipe. If the pipes are flared out, e.g., if a narrow supply pipe is enlarged to the input cross section of a chamber, then turbulence is created in the outer zones of the core flow, which leads to a further disturbance of the distribution in the vicinity of the pipe walls.
In order to distribute a flowing medium over a flow cross section, the above-mentioned prior art devices, as above-noted, typically employ a distributor plate which extends over the entire flow cross section and which has a multiplicity of openings. Such a distributor plate causes the flowing medium to back up and, thus, to distribute over the plate openings. Its effectiveness, however, depends heavily on the prevailing flow conditions. In particular, if, for a given size and arrangement of the plate openings, the mass throughput through the device is too low, a sufficient backing-up effect and distribution of the media will not occur. Conversely, with too large a mass throughput, the backing-up effect of the distributor surface is so large that a substantial pressure and energy loss occurs at the distributor, which is undesirable in many applications. Added to the latter, is the fact that the effectiveness of the distributor plate also depends to a considerable extent on the flow conditions following the distributor surface. Thus, the flow resistance can increase in certain regions, for example, in a packing bed following the distributor surface, due to impurities. As a result, the mass throughput through these regions drops and the desired uniform distribution is distributed.
German Auglesgeschrift No. 1,138,290 discloses a multi-stage device for breaking down high pressures and for regulating media flowing under high pressure which contains in each stage a stationary seating part with throttle openings and an associated movable closing member, by which the throttle openings can be released or shut off. The closing member may be realized as a piston slider, a plane (gate) slider or a rotary slider. The device serves to dissipate the pressure energy of the flowing media with as little vibration and noise as possible as well as without forming vortices; therefore, a pressure loss as high as possible is desired. The throttle openings can be arranged in two opposite quadrants of a disk-like member forming the seating part, the closing member being designed as a cover plate and having sector-shaped cutouts in two opposite quadrants. By rotating the cover plate, the openings are covered up in part or totally, and the total passage cross section of all openings is thus determined. The seating part and the closing member can also be designed as concentric rings with openings and passages arranged along their circumference, whereby the free passage cross section of each opening can be varied by rotation of the closing member. With such an arrangement, uniform distribution of the flowing medium over the entire flow cross section of the device is not achieved.
It is an object of the present invention to provide a device for distributing the media flowing from a supply pipe so that it can be distributed over the flow cross section uniformly or in any other desired manner. It is a further object of the invention to provide such a device so that it can be adapted to flow conditions prevailing in a particular case in such a manner that pressure loss is kept low.